This invention is directed to an apparatus and method for the wet processing of solid materials wherein the material may be automatically and sequentially subjected to a plurality of processing solutions or washes. More particularly, the present invention is directed to the automated wet processing of wafers used in the semiconductor industry.
The fabrication of semiconductor devices typically involves many different types of processes. Photolithographic techniques utilize solutions to develop photo resist patterns and to chemically etch the exposed wafer surface. In addition, thin film deposition on wafer surfaces can be accomplished by electroplating or chemical-reduction plating from solution. Successful fabrication requires precise control over such processes as well as quality control over the presence of particulates which contribute to device failure.
Devices for the automatic movement of solid materials through a series of process stations are known. For example, U.S. Pat. Nos. 2,534,338 and 3,335,839 disclose apparatus for transferring racks to a series of treating stations.
However, such apparatus do not provide a centrifugal drying means to ensure that the treated material is free from particulate or liquid matter between successive treatment stations.
In the semiconductor industry, the movement of wafers through wet process stations is performed primarily by human operators. This introduces the possibility of operator error affecting the time the wafers are exposed to process solutions, variation in the drying time before the wafers are exposed to the next process, contamination of the process solutions and physical damage to the wafers. Additionally, human manipulation introduces the potential for contamination of the wafers by operator particulates.
There is a need, therefore, for an apparatus and method whereby the sequential wet processing of solid materials, particularly, semiconductor wafers, may be performed with a high degree of reproducibility in a environment where particulate contamination may be substantially eliminated.
Accordingly, an object of the present invention is to provide methods and means for automated sequential wet processing of solid material which have a high level of reproducibility through the elimination of operator error and contamination by operator particulates.
A further object of the present invention is to provide methods and means whereby process solutions may be quickly removed from the materials being processed to facilitate uniformity in the process and the minimization of contamination of subsequent process solutions.
Still further, an object of the present invention is to provide methods and means whereby automated sequential wet processing may be interfaced with automated loading-unloading devices and transport systems.